arethusa's Journal

June 20, 2019

Today I'm presenting one of my methods I thought of for orchid identification, which are new to the best of my knowledge. I do not, unfortunately, have enough data to make them work—nor have I tested them enough to assess their accuracy—so this will be very casual and require that any reader takes innumerable pinches of salt. If these new ideas don't go anywhere, they can at least be food for thought.

See the link below for a draft of the visual method and an explanation. I'll be referring to my methods as #1 (this post) and #2 (the next).

October 26, 2018

Platanthera psycodes (Bigelow) Lindley and Platanthera grandiflora (Linnaeus) Lindley , with their superficial similarity, are a source of challenge and confusion for nature enthusiasts and botanists alike. Platanthera shriveri P.M. Brown (Fig. 9), a controversial taxon first described in 2009, is separated from P. grandiflora by the following characteristics, as described in a segment of the key presented in "A New Species of Fringed Platanthera From the Central Appalachian Mountains of Eastern North America" (Paul Martin Brown, Clete Smith & J. Scott Shriver): "lip segments deeply and compoundly lacerate; isthmus slender, length ca. 4 times the width; spur 2-2 1⁄2 times the length of the lip; orifice angled at top."

Some experts have chosen to recognize Platanthera shriveri as an ancient hybrid between Platanthera lacera and Platanthera grandiflora, while others believe P. shriveri to be one and the same as Platanthera grandiflora.

Platanthera ×enigma P.M. Brown was described as a hybrid between Platanthera grandiflora and Platanthera psycodes and can be found in areas where the flowering time of Platanthera grandiflora and P. psycodes (which typically flowers later than P. grandiflora) overlap. Mixed populations in Maine, which is one such area, should be examined closely!

The most reliable characteristics one can use are the shape of the orifice (the opening to the spur/nectary/mentum) and the shape of the rostellum lobes. Platanthera psycodes has an opening shaped like an transverse oval/dumbell (Figs. 6, 7), while Platanthera grandiflora has a rounded opening (Figs. 2, 8). As for the rostellum lobes, Efloras.org sums it up perfectly in couplet 6 of their key to Platanthera. P. grandiflora is described as having "Rostellum lobes spreading, angular in lateral view.", and P. psycodes is described as having "Rostellum lobes parallel, rounded in lateral view."

The raceme on Platanthera psycodes is more slender than that on Platanthera grandiflora, often producing far more flowers of a smaller size and tapering off to a point (with the buds) at the top. It is important to note that flowers on the lower portion of the raceme on P. psycodes usually shrivel before flowers on the upper portion break bud, in contrast to P. grandiflora, where all the flowers on the raceme end up open simultaneously. It is also important to note that, when viewed from above, the raceme on P. psycodes also appears remarkably circular.

The labellum, or lip, is a specialized petal found on all orchid species, serving a variety of purposes and is often integral to the flower's pollination. In Cypripedium , the labellum is pouch-shaped (hence the name "Lady's-slippers"), on Calopogon , it is hinged. Some Platanthera species have a labellum that is entire and unlobed (e.g. Platanthera dilatata), while others have a labellum that is unlobed and fringed (e.g. Platanthera blephariglottis, or, as in Platanthera grandiflora and Platanthera psycodes, three-lobed and typically fringed.

The labellum on Platanthera grandiflora is usually deeply fringed and the lateral lobes (Fig. 3) are dramatically upswept. This is very different from that on Platanthera psycodes, which has far less fringing on the margin and lateral lobes (Fig. 5) that aren't, or are hardly upswept at all, sometimes even appearing to droop down.

As always, use the shape of the opening and rostellum lobes whenever possible, as they are the most reliable, but keep the other characteristics in mind. I'm not sure how reliable it is to use habitat, but I have noticed that Platanthera grandiflora seems to grow more commonly in forests than Platanthera psycodes, which seems to prefer very wet, open areas.

April 16, 2018

I will be in Ecuador from April 16th-May 1st, and will not have my computer with me. For this reason, I will be completely inactive on iNaturalist until I get back and begin to upload the copious amounts of photographs I will take of orchids and other interesting things. The places of interest we (we being my me & my parents) will be visiting are Baños, Puyo, Macas, Sangay National Park & Los Cedros.

October 20, 2017

I was delighted by how well received the comparison between the purple fringed orchids was and decided to make more illustrations for identification purposes. As requested, I will be focused mainly on Spiranthes for the time being. S. magnicamporum was considered the same species as S. cernua up until 1973. It can often be distinguished from S. cernua by the flared lateral sepals, the lack of basal leaves, the yellow thickened area on the labellum and by the shape of the flowers. S. cernua will often have a white labellum and basal leaves should be present while in flower. However, morphological differences can often be misleading since S. cernua is a species complex, and will occasionally exhibit traits from S. magnicamporum . Perhaps the best way to distinguish between the two is to examine the seeds, which are often polyembryonic on S. cernua, unlike those produced by S. magnicamporum@sambiology and @eraskin, it is done! I will continue to make other illustrations throughout the year. Hope this is helpful.

October 08, 2017

P. grandiflora vs. P. psycodes
Purple fringed orchids are hard to mistake for any other flower, yet when faced with deciding between the lesser purple fringed orchid (Platanthera psycodes) and the greater purple fringed orchid (Platanthera grandiflora), it can be difficult to settle on an ID.

First off, if you find a purple fringed orchid, it is more likely to be P. psycodes, since it is more common than P. grandiflora. Flowers on P. psycodes are often smaller and wither on the bottom before the buds on top open, whereas on P. grandiflora the flowers on the bottom typically remain open longer. The most reliable characteristics are the spur opening (round on P. grandiflora) and the rostellum lobes (with “tails” on P. grandiflora).

Before using any of these tips, remember that my drawings aren't perfect and that no individual orchid is exactly alike. Also take care not to be thrown off by color variations, lack of fringing, etc

July 05, 2017

Photographing orchids in the genus Malaxis is an arduous task, especially while under attack from mosquitoes, soaked in water and in poor lighting. A year or two ago, we attempted to photograph a couple Green Adder's Mouth that we had heard were growing in New Hampshire, following vague instructions deep into a wooded area that we had never been to before. It was in those woods that we searched for hours, finally finding the plants at dusk. It was then too dark to photograph them. We ended the trip tired, hungry, mosquito bitten and dreading the long drive to come, looking over a couple low quality photos. This time wasn't that much different. The orchid was in a patch of moss growing next to a small stream that emptied out into a fen, and was shaded by the trees to the point that the camera couldn't photograph anything. I found myself squatting in the water, one hand operating the lens, the other behind the plant to focus the camera in addition to using a cellphone flashlight. If you didn't know, flowers on Malaxis are tiny. Two millimeters tiny. They're also a faint green. I was adamant about getting the perfect shot, but eventually the mosquitos (Which are biting me now, I might add) drove us away, leaving us with only three good photographs. Malaxis always gives me trouble, and I can only expect to have more of the same in the days, months and years to come.